Step-by-step explanation:
The cylinder is a closed figure which consists of two circular ends. If r is the radius and h is the height of the cylinder, then its surface area is given by :
or
We also know that, surface area = perimeter×height
So, the surface area of the cylinder is the product of circumference of the circle and height of the cylinder.
Answer:
see explanation
Step-by-step explanation:
The nth term of an AP is
= a₁ + (n - 1)d
where a₁ is the first term and d the common difference
Given a₅ is double a₇ , then
a₁ + 4d = 2(a₁ + 6d) , that is
a₁ + 4d = 2a₁ + 12d ( subtract a₁ from both sides )
4d = a₁ + 12d ( subtract 12d from both sides )
- 8d = a₁
The sum of n terms of an AP is
=
[ 2a₁ + (n - 1)d ] , substitute values
=
( 2(- 8d) + 16d)
= 8.5(- 16d + 16d)
= 8.5 × 0
= 0